1. Field of the Invention
Aspects of the present invention relate to an ink level detecting device functioning as a cover opening sensor in an ink-jet image forming apparatus, and more particularly, to an ink level detecting device that can also function as a cover opening sensor by using a plurality of electrodes arranged in parallel with each other.
2. Description of the Related Art
Generally, ink-jet image forming apparatuses form images by ejecting ink through an ink ejecting head. Examples of the ink-jet forming apparatuses include ink-jet printers, ink-jet copy machines, facsimiles, all-in-one printers, and the like.
An ink-jet image forming apparatus receives ink from an ink container such as an ink cartridge. The ink filled in the ink container is supplied to the ink ejecting head directly or through a predetermined ink supply passage and ejected in response to a print signal. As an image forming process is being performed, the amount of ink filled in the ink container is reduced and the ink level in the ink container is lowered. When the ink level reaches a minimum level, either the ink container must be refilled, or the used ink container must be replaced with a new ink container.
Therefore, a conventional ink-jet image forming apparatus includes an ink level detecting device which detects the ink level in an ink container. Also, a main body of the image forming apparatus has an ink container mounting unit and a cover for opening and closing the ink container mounting unit. In addition, the ink-jet image forming apparatus includes a cover opening sensor which senses the opening and closing of the cover and transmits a signal to a central processing unit in the main body so that the cover opening state, i.e., the status of whether the cover is open or closed, can be displayed through a display unit and properly controlled.
A reflective or transmitting photo sensor, a magnetic sensor, a contact type switch sensor, and the like have all been widely used as various types of cover opening sensors. However, in the conventional models, the cover opening sensor is an independent unit from the ink level detecting device and is usually mounted on the ink container itself or is mounted on an ink container mounting unit, thereby requiring the image forming apparatus to have a special internal connecting structure. Thus, the conventional image forming apparatus has a complicated structure because its cover opening sensor and ink level detecting device are independent of each other, and the manufacturing cost thereof is expensive.